1. Field of the Invention
This invention relates to a new internal fixation boneplate for long bone fracture, which is characterized by its Z-shaped cross section.
2. Prior Art
The currently used methods for internal fixation of long bone fractures are mainly the following:
(1) Fixation of transplanted massive cortical bone with screws.
(2) Internal fixation with intramedullary nails. This is presently the most commonly used clinical method.
(3) Penetrating fixation with screws.
(4) Fixation with screw plate.
(5) Fixation with compression plate and screws.
The common drawbacks of the above 1 to 4 methods are: long period of postoperation extra immobilization with plaster; unreliability in fixation of a fractured bone; lengthening of the recovery period; arrest of bone growth and development caused by screws; frequent occurrence of bending or broken of the plate and screws which leads to failure of the operation, and having another operation to pull out the screws is very complicated and increases the patient's pain.
Method 5 is a new method which has been popularized during the past 20 years. According to the principle that the closely contacted compression stress between the fractured sections will speed up the recovery, fixing the plate with screws enables the fractured ends to press closely to each other along the bone axis so that the healing period is shortened with no requirement for postoperation extra immobilization. The patient can move a little such as sitting up, turning the body over, etc. One shortcoming of this method is that the big boneplate brings great stimulation to the tissue and should be taken out through a second operation and hence high expense is needed. The major shortcoming of this method is that due to its firm fixation, it is the plate, rather than the bone tissue that the plate fixes, that bears the whole stress conducted from the load limb bears. This hinders the remodeling of the bone construction according to the conduction of its physiological stress during the healing period and causes bone atrophy. As a result, fracture may occur at the end of the plate where normal bone and cancellated bone meet, and refracture may also occur after the plate is removed. These are the bad effects caused by the blindness of increasing the plate bearing load. The present invention overcomes all the above mentioned shortcomings with its specific advantages.